The invention relates to a stackable transport and storage container.
Transport and storage containers of this type are used in particular wherever tools or components are to be transported or temporarily stored as part of a manufacturing process. They are typically composed of metal sheets or plastic sheets, which are glued, welded or positively joined to each other. In addition to sufficient load-bearing capacity and a sufficient service life, it is also important that the containers preferably do not have any protrusions or projections that constrict the interior space or are an impediment otherwise.
While containers made of metal are relatively stable, they are often quite heavy and susceptible to corrosion, and use of the same creates excessive noise. Containers made of plastic materials have the advantage that they have a relatively low weight. On the other hand, they often have only low stability, which is compensated for by added reinforcements.
For comparable usages, injection-molded containers and containers produced from PR (polypropylene) twin-wall sheets of various designs are known. The injection-molded containers are containers produced in complex molds. Due to the high tooling costs, these can only be produced effectively in large quantities.
Comparable PR twin-wall containers are either characterized by being joined from a large number of individual parts, necessitating multiple individual work steps, or by simple folding and bending constructions, which are held so as to maintain the shape thereof by way of a peripheral stacking profile. For this purpose, thermal bending, ultrasonic welding techniques, bonding techniques, and other joining and processing operations are employed. In principle, the containers are characterized in that it is possible to also produce smaller quantities having a wide variety of dimensions, due to the lower tooling costs.
EP 1 505 001 A1 describes a stackable tote box made of thermoplastic resin for storing small parts of all types or for single-use or multi-use transport of the same. The tote box is always produced from thermoplastic resin. It comprises a bottom and usually four side walls, which are produced from a planar starting plate. This starting plate is preferably a twin-wall sheet.
Linear notches are introduced between the bottom and the side walls, about which the side walls can be folded to form a box-shaped base body. The abutting vertical edges of the side walls are welded together. A turnover rim adjoins at the upper edges of the side walls, which is folded 180° about linear notches in the starting plate against the respective side wall. A stacking profile is positively clipped over the turnover rim so that a protrusion integrally formed on the stacking profile secures the stacking profile on the turning rim.
A respective stacking corner can be attached at the corners, which includes a connecting piece shaped similarly to the turnover rim and extends the shape of the same. The stacking profile is positively clipped between the stacking corners over the turnover rim and over the connecting piece so that a protrusion integrally formed on the stacking profile secures the stacking profile on the turnover rim and the connecting piece. The stacking corner and the stacking profile usually have the same peripheral shape.
Due to being cut to size from a “Swiss cross”, separate scrap pieces result at the corners, which are reusable by being inserted as corner brackets for lateral reinforcement.
The horizontal forces at the upper rim of the tote box are to be absorbed by vertical weld joints connecting the side walls to each other. This effect can additionally be increased by corner brackets glued on at the side. The long weld seams, however, make the manufacturing process very complex, and the provision of the additional corner brackets increases the complexity yet again.
The manufacturing process is very time-consuming and susceptible to errors. In particular, there is the risk that poor weld joints will occur and perpendicularity is not ensured. For large-volume orders, special profile lengths have to be produced, and warehousing requires much space.
EP 0 874 595 B1 describes a stackable transport container comprising a self-locking upper rim. The container is composed of a uniformly thick, foldable container blank, comprising a bottom, two upright end walls, two upright side walls, and four end flaps. The side walls and the end walls have downwardly folded tabs, over which an upper rim is placed, which automatically engages the tabs.
Horizontal forces are absorbed by the peripheral, single-piece top rim and by added corner reinforcements or insertable corner profiles. Separate rims thus have to be provided for each container size. Due to the large number of added corner pieces, production and assembly are very complex.
A tote box is known from DE 295 17 973 U1, in which the side walls are twin-wall sheets made of thermoplastic resin. The upper edges of the side walls are provided with a turnover rim, which is integrally formed on the side walls in one piece and formed by a rigid bent edge of the twin-wall sheet. This results in the formation of a peripheral cavity. The lower end of the turnover rim is separated from the side walls by an open joint. At the sides and corners, the side walls are held together positively by way of connecting pieces using rim, folding and side connectors. The described tote box has a complicated construction comprising a large number of protrusions, edges, and projections. The production of the same is very complex as a result of the large number of individual parts.
In U.S. Pat. No. 5,037,027 A, a folded base plate is shaped to obtain a container. U-shaped profiles are pushed over the upper rim. Corner pieces reside in the four corners, which are shaped so as to extend over the U-shaped profiles, where they are secured by way of pins. An upper rim is integrally formed on the corner pieces, which ensures that the container can be stacked. The pins also retain the side walls in the U-shaped profiles. The horizontal and vertical forces are absorbed by the corner pieces fastened to the peripheral profiles by way of pins, and furthermore by the angular profiles fastened additionally to the vertical corners. A very large number of individual parts is needed to achieve adequate stability. By virtue of the superimposed corner part, projections and protrusions are created, which may be disadvantageous.
U.S. Pat. No. 2,544,283 A describes a transport container made of a folded blank. It comprises a top rim having a lip on the underside, which engages in the side flaps of the erected container. The rim is composed of two regions, which are held by connecting clips.
Folded containers having a peripheral stacking rim at the top are also described in U.S. Pat. No. 2,941,710 A or NL 6 612 391 A.